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10/6/2014: Federal agents say they found "multiple handwritten documents that appeared to be drafted by Khan and/or others, which expressed support for ISIL." NBC 5's Charlie Wojciechowski reports. (Published Monday, Oct. 6, 2014)

A 19-year-old man from southwest suburban Bolingbrook was arrested Saturday at O’Hare International Airport for allegedly attempting to travel overseas to support terrorism.

The man, identified as Mohammed Hamzah Khan, was charged Monday with attempting to provide material support to a foreign terrorist organization operating inside Iraq and Syria. Khan was arrested without incident on his way to Vienna and then Istanbul to allegedly fight for ISIS, prosecutors said.

Khan appeared in federal court Monday morning before U.S. Magistrate Judge Susan Cox in Chicago and remains in federal custody pending a Thursday morning detention hearing.

According to the complaint affidavit filed Monday, a round-trip ticket was purchased for Khan on Sep. 26, from Chicago to Istanbul. He was scheduled to depart Saturday and return on Thursday.

Khan was stopped by U.S. Customs and Border Protection officers at O'Hare while passing through the security screening checkpoint Saturday afternoon and interviewed by FBI agents at the airport.

While executing a search warrant at Khan’s residence, federal agents found "multiple handwritten documents that appeared to be drafted by Khan and/or others, which expressed support for ISIL," according to the affidavit.

One of the items, according to the affidavit, was a handwritten letter that appeared to have been written by Khan and left in his bedroom to explain his travel to his parents.

The affidavit alleges the letter instructed his parents not to contact police about his trip and informed them he was on his way to Syria.

“First and foremost, please make sure to not tell the authorities, for if this were to happen it will jeopardize not only the safety of us, but our family as well," the letter read, according to the affidavit.

The letter read there was an obligation to “migrate” to the “Islamic state” now that it has “been established.”

Khan's Bolingbrook neighbors are upset and concerned about the arrest.

"I see the people every day when I am coming home from work doing whatever they do across the street there. You never think you have terrorists living on the same block as you. That's scary," neighbor Daniel Arnold said.

"A couple of my friends were like, "watch out for that house." I am like, 'don't be like that,' and, low and behold, they were right I guess," neighbor Steve Moore said.

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